Capitulum

Part of speech: noun

Definitions

1. A structured cluster of flowers or the head of a plant that blooms in a round shape is known as a floral arrangement or aggregate
2. It refers to a form of inflorescence where multiple flowers grow closely together on a single stem
3. The term can also signify a round or flattened structure that serves as a reproductive unit in different plant species

Etymology: Latin "capitulum" is the diminutive of "caput", "head", so it literally meant "little head". Botanists borrowed it for a compact cluster of tiny flowers packed onto a common stalk, the kind seen in clover, daisies and thistles, where many separate blooms look like a single flower. The sense makes sense: each dense cluster presents itself as one head. The same Latin word had other lives in English. Through Old French it gave us "chapiter", the decorated top of a column, and "chapter", a division of a book or, originally, a section of a religious house's rule read aloud to the community. These are doublets: words from one source that entered a language by different routes and took on different meanings. "Capitulum" itself stayed in the technical vocabulary of botany, where it is still the standard term for this kind of inflorescence.